Characteristics of brown earth soils
These include: climate, relief, soil drainage, parent material and the soil biota that live in the soil itself. General relations in western Europe[ edit ] Brown Earths are important, because they are permeable and usually easy to work throughout the year, so they are valued for agriculture.
Podzols are easily recognisable by their distinct layers or horizons. Two factors have influenced the development of these soils: Sufficient depth of soil parent material, which is neither extremely siliceous nor extremely calcareous, and which is permeable to permit free aeration.
They are freely drained soils with well-developed A and B horizons.
Characteristics of peaty soil
At the base of the slope we usually find a concave area where the eroded soil has accumulated. Under natural conditions the soils would form under broadleaf forest which promotes rapid decomposition of plant residue and consequent recycling of plant nutrients. For example, in the UK reddish brown earths occur on the Old Red Sandstone Devonian and the New Red Sandstone Permian , and are red because the rocks from which they formed are derived from strongly oxidised deposits that were laid down under desert conditions millions of years ago. Bw Brightly coloured mineral subsoil, with good structural development, generally merges into: C Relatively unaltered parent material, usually brightly coloured or colour inherited directly from parent rock. They often develop over relatively permeable bedrock of some kind, but are also found over unconsolidated parent materials like river gravels. The processes of weathering and plant growth that were responsible for the formation of soils from bare parent materials in the first place are still going on. A grey or light-coloured 'E' horizon is the result of severe leaching, or eluviation, which washes out everything but quartz grains. Podzols are easily recognisable by their distinct layers or horizons. These are rather similar to brown earths, and some other classifications, including the British and French, call these soils argillic brown earths sol brun lessive , because they have an argillic, i. Two factors have influenced the development of these soils: Sufficient depth of soil parent material, which is neither extremely siliceous nor extremely calcareous, and which is permeable to permit free aeration. The top of the hill is usually convex, and it is here that most erosion is taking place — upper slopes and summits are more exposed to wind, and rain, and gravity is slowly but surely moving the topsoil down the hill. Brown earths are also classified in the German and Austrian soil taxonomy as "Braunerde.
They often develop over relatively permeable bedrock of some kind, but are also found over unconsolidated parent materials like river gravels. The iron and aluminium oxides collect in the 'B' horizon where the iron oxides can accumulate to form a thin layer of hardpan, which impedes drainage through the soil.
The acidic conditions are not liked by soil organisms which would normally merge the boundaries of the horizons.
Soil formation factors[ edit ] A brown earth soil is affected by several different factors. The rich colour is the result of iron compounds, mainly complex oxides which, like rust, have a reddish-brown colour. If the breakdown is slower, moder humus is formed.
We think, perhaps of soils as static and unchanging, but in fact they are never stationary. Thus soils on the brow of the hill tend to be shallower than those in mid-slope positions, where soil is moving down, but being replaced by material from above.
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